A number of eavestrough systems are currently marketed and in the do-it-yourself market, there are two basic types of systems. The first system is a solvent welded or secured system where plastic pieces are inserted, one into the other and then adhered, to provide a positive securement and seal therebetween. The second type of system involves fittings and eavestrough where the eavestrough snaps into the respective fitting, and the fitting includes a gasket member for providing a seal with the outer surface of the eavestrough. Examples of this second type of system are shown in U.S. Pat. No. 4,257,716.
Any system which uses plastic eavestrough must be of a design to allow for thermal expansion and contraction of the eavestrough with changing ambient temperature. This thermal expansion is accommodated in the second type of system by providing within the fitting room for thermal expansion of the eavestrough whereby the eavestrough moves within the fitting with the gasket maintaining the seal. Thus, the gasket accommodates the moving of the eavestrough within the fitting.
Problems can occur with respect to moving seal systems due to the movement of the eavestrough and due to forces exerted on the base of certain eavestrough, as disclosed herein and in U.S. Pat. No. 4,257,716. This base can bow upwardly, partially due to the shape of the eavestrough and the manner in which the eavestrough is snap fitted into the fitting. The bowing of the base of the eavestrough is also compounded by thermal expansion of the eavestrough during the hot summer months which provides additional stress on the walls of the eavestrough, resulting in the base portion bowing generally in the center of the eavestrough fitting.